Field of the Present Disclosure
The present disclosure relates to circuitry for memory devices, and more specifically, to systems and methods for write preambles that may be used during the writing of data of a memory device, such as a double data rate (DDR) memory device.
Description of Related Art
Random access memory (RAM) devices, such as the ones that may be employed in electrical devices to provide data processing and/or storage, may provide direct availability to addressable data stored in memory circuitry of the device. Certain RAM devices, such as synchronous dynamic RAM (SDRAM) devices may, for example, have multiple memory banks having many addressable memory elements. A strobe-based data bus may be used, in combination with certain strobe signals, to provide read and write access to the addressable memory elements. The data strobe signals (e.g., DQS) may include a programmable preamble portion, a toggling portion, and a postamble portion. The programmable preamble portion may provide for a programmable timing window for the receiving device to enable data capture circuitry while a known/valid level is present on the strobe signal, thus avoiding false triggers of the data capture circuitry. Following the programmable preamble portion and during the toggling portion, the DQS will toggle along with a clock signal (CLK) through high and low transitions to transfer data. Time following the last transition is then known as the postamble portion.
A phase difference between the CLK and DQS strobes (tDQSS) may create a domain crossing problem for the start of write bursts. That is, an activation period of the signal synchronized with the external data strobe signal DQS should be maintained until the internal clock is activated to ensure proper functionality. This domain crossing problem is made worse when write commands are issued so close together that the programmed write preamble is incomplete, which reduces the time window needed to resolve the domain crossing. It would be beneficial to improve techniques for programmable write preambles.
Embodiments of the present disclosure may be directed to one or more of the problems set forth above.